Assume one of pads in a rectangle shape with arbitrary sides is placed in quadrant 2. The other pad is also in a rectangle shape and with arbitrary sides placed in quadrant 4. I would like to find the capacitance between these two. The method I am using is Conformal Mapping, just like what is used for finding the capacitance for a case of co-planar wave-guide. The problem is that I first need to put these two rectangles in parallel where the center are also in line with each other and I cannot find a mapping for that. I am attaching a picture for clarification.